This helps in the penetration of egg by the sperm

The correct option is sperm lysin.

During the process of fertilization, a sperm must penetrate the protective outer layers of the egg (ovum) to fuse with its membrane. These protective layers include the corona radiata and the zona pellucida.
To overcome these barriers, the acrosome (a cap-like structure at the head of the sperm) undergoes the acrosome reaction. During this reaction, it releases specialized enzymatic secretions collectively known as sperm lysins.

These lysins include:
1. Hyaluronidase: An enzyme that dissolves the hyaluronic acid cementing the cells of the corona radiata together.
2. Corona penetrating enzyme: Helps the sperm digest its way through the corona radiata.
3. Acrosin (or Zona lysin): A proteolytic enzyme that digests the zona pellucida, creating a path for the sperm to reach the plasma membrane of the egg.

Therefore, sperm lysin is the key agent that facilitates the penetration of the egg by the sperm.